Each year, almost five million people are bitten by dogs. About 800,000 of them require medical care, and more than 300,000 of them will require emergency medical treatment. While deaths remain uncommon, each year people are killed in dog attacks, with 80% of fatalities occurring among children.
At common law, the owner of a dog could be held liable only if the owner knew the dog to be dangerous. This gave rise to what has become known as the "one bite rule" - a dog is not presumed to be dangerous until it bites, and thus the first person it bites cannot bring a claim against the dog owner as the owner is not "on notice" that the dog is dangerous. Once the dog has bitten somebody, it is presumed dangerous and thus the owner can be held liable for subsequent dog bites or attacks.
There are circumstances under which the "one bite rule" can be avoided. Sometimes it is patently obvious that a dog is dangerous, whether by virtue of its temperment, training, or treatment, before its first bite. For example, a dog owner can't train a dog for dog fights, and then claim that he had no idea that the dog might be dangerous when the dog bites a person. There may be additional exceptions which can give rise to liability, such as the failure to follow laws or ordinances requiring that a dog be properly caged or kenneled, or that it be kept on a leash.
Many jurisdictions have enacted statutes which do away with the "one bite rule", and make dog owners liable for most or all bites and attacks by their dogs. Such laws may also extend to those exercising custody or control over a dog, such as a dog walking service or a dog sitter. These dog bite laws can vary significantly from each other, and the defenses that remain available to dog owners can also be very different from state to state. Common defenses include:
Provocation: The victim of the dog bite did something to provoke the dog. This may be an actual provocation, such as teasing the dog, poking or hitting it, or taking away its food. Depending upon the law, it might also be an inadvertent, such as picking up a dropped piece of food even where the victim isn't aware that the dog has fixed its attentions on the food.
Assumption of Risk: A professional dog trainer working with a client's dog will generally be held to have assumed the risk of being bitten, and thus won't be able to bring a dog bite claim against the owner.
Trespassing: Some states do not permit trespassers to bring actions for dog bites they suffer during the course of their trespass.